Advertisement
1.
Unplug ac cable from ac power source
.
2.
Remove screws that secure top cover to
main frame. Lift front edge of cover and
pull cover forward to clear rear lip from
chassis. Lift cover off.
3. Locate terminal board TB101 (Figure 7).
Disconnect top lead from terminal 1 and
reconnect to terminal
2.
Disconnect top
lead from terminal
4
and reconnect to
terminal 3. This wiring change modifies
the main frame to operate at 8 ohms
load impedance
.
4.
For each power amplifier module used
with a modified main frame, locate jump-
ers J8A and J8B on component side of
module (Figure 7). Remove these two
jumpers to modify each power amplifier
module to operate at B ohms rated load
impedance
.
....------
CAUTION-----~
The 8-ohm modified
power
amplifier
module may
not
be used in a main
frame not modified as in Step
3.
To
avoid possible mixup
,
clearly tag or
mark the 8-ohm modified modules
"for 8-ohm operation only". Similarly
,
the modified main frame should be
tagged for "8-ohm operation only".
5. Install top cover of main frame and
secure with screws previously removed
(Step
2).
Note that all card modules may
require removal and re-installat ion after
top cover is secured, to assure proper
alignment in card guide channels
.
6. Install modified power amplifier modules
in main frame.
SETUP AND OPERATION
MODULAR BLOCK DIAGRAM
The Modular Block Diagram Kit consists of
a simplified
Main Frame Wiring Diagram
(42-02-045233) with designations
for con-
necting power amplifier modules
.
To com-
plete the Main Frame Wiring Diagram, sel-
ected module diagrams are taken from the
Modul
e Diagram
Sheets (42-02-045232) and
affixed to approp
riat
e spaces
wit
hin
t
he
Main Frame Wiring
Diagram. The Main
Frame Wiring Diagram then becomes the
Modular Block
Diagram.
Switch and cable
connections are then drawn on the Modular
Block Diagram to complete a orawing of the
system configuration
.
The finished Incre-
mental Power System block diagram may be
copied on any standard blue-line machine or
othe
r
large-format copier
.
To use the Modular Block Diagram Kit in an
orderly
way,
1.
Choose input
,
driver
,
and power amplifier
modules as needed from the Module Dia-
gram Sheets
.
Remove the module dia
-
grams from
t
he sheets and carefully affi
x
each module diagram to the appropriate
space on the Main Frame Wiring Dia-
gram. Pressure-sensitive adhesive on the
back of the module diagrams will hold
them securely
.
Do not allow the adhesive
to touch the Main Frame Wiring Diagram
until the module diagram is oriented
accurately
.
2.
Indicate switch closures on the driver
matrices
by drawing a line between
switch contacts, or by circling the entire
switch
,
or both
.
As necessary
,
refer to
setup procedures for the appropriate
driver module
.
3.
Draw simplif ied loudspeaker connection
diagrams to the right -hand side of the
power amplifier modules
.
As necessary
,
refer to OUTPUT CONNECTIONS in this
manual.
4.
Make as many copies of the fin ished
Modular Block Diagram as required
.
Finished examples of the Modular Block
Diagram are illustrated
in Figures
19
through 23. Additional Modular Block Dia-
gram Kits may be orde red from the AL TEC
Literature
Depart
ment. For each kit desired
,
ask for one copy of the Main Frame Wiring
Diagram,
AL-1212 (42-02 -045233) and one
copy
of the
Module
Diagram Sheets,
AL-1213 (42-02-045232)
INPUT CONNECTIONS
All input connections
to preampli
f
iers or
other
signal
processing
equipment
are
made at
t
he rear panel of the main frame
(Figure
8).
Connec
t
ions should be made
with two-conductor
,
twisted-pair shielded
cable such as Belden 8450 or 8451.
For balanced input at the CH-1 through
CH-4 receptacles
,
the Model 2221
(trans-
former isolated) Input Card Module must be
installed in the input module slot of the
main frame
.
For unbalanced inpu
t
at the
UN-
BAL jacks
,
either the Model 2220
(trans-
formerless) Input Card Module or the Model
2221 Input Card Module may be installed
.
If electronic c rossover is to be inco
rpor-
ated, the Model 2251 Crossover Driver Card
Module must be installed in the appropriate
locations. Inputs for electronic crossover
are dedicated at CH-1 and CH-3 BAL or UN-
BAL
INPUT.
The CH-1 connector requires a
crossover driver module to be installed in
the main frame at the #1 (left) drive
r
module
posit
ion;
the CH-3 connector
requires a
crossover driver module to be installed in #2
(right) driv
er
module slo
t.
Always be sure to use the correct plug in
the main frame connectors (Figure
8).
The
J213 thru J216 receptacles require use of
stereo phone jacks
.
~-----
CAUTION-----~
Standard phone plugs (tip and sleeve)
will short-circuit internal wiring when
inserted in jacks J213, J214,
J215,
or
J216.
Unbalanced Inputs
For unbalanced inpu
t
signals connected to
the UNBAL INPUT jacks of Channels .CH-
1
thru
CH-4,
install the Model 2220 Unbal-
anced Input Card Module in the input module
slot of the main frame. Each of the four
channels has two UN BAL jacks wired in par-
allel; this makes available a convenient
signal to feed a second Incremental Power
System, a Model 9440 Power Amplifier, or
other alternate unit.
J8A
J8B
MODEL
2275
POWER
AMPLIFIER
MODULE
MAIN
FRAME
Figure
7.
Modification of Main Frame and Power Amplifier Modules for 8-Ohm Operation
5
Advertisement
